Distillation of tar or pitch



Jan. 2, 1934. p s. P. MILLER 1,942,372

DISTILLATION 0F TAR 0R PITC Filed June 25, 1929 i Q/ (IENTOR ATTORNEYSPatented Jan. 2, 1934 PATENT OFFICE DISTILLATION F TAR on rrrcn StuartParmelee Miller, Englewood, N. J., as-

signor to The Barrett Company, New York, N. Y., a corporation of NewJersey Application June 25, 1929. Serial No; 373,646

14 Claims.

This invention relates to the distillation of tar or pitch, theproduction of modified tars, the production of coke and the operation ofby-product coke oven plants. v

More particularly, the invention comprises an improved process fordistilling tar, pitch, etc., in which the tar is introduced into a cokeoven above the charge of coking-coal therein and distilled with more orless decomposition to produce pitch coke and modified distillates and inwhich the distillates are drawn ofi together with the gases from thecoking of the coal and cooled iorthe recovery of modified tar productstherefrom.

In the ordinary operation of by-product coke oven plants the gases froma number of ovens are collected together in a common collector main andpassed to a condensing system. The gases are cooled in the collectormain and in the condensing system and the heavier tar is usually drawnoff from the collector main and a lighter tar from the condensingsystem. The combined tar is commonly shipped to tar distillation plantsand there distilled. It can also be distilled in stills provided at thecoke oven plant.

The present invention provides an improved process in which thedistillation of the tar or pitch is carried out directly in the cokeoven so that the coke oven serves not only for the coking of the coalbut also for the distillation of the tar or pitch and the coking of theresidue.

The invention is of particular value for the production of modified tarssuch as special high carbon tars and high carbon pitches derivedtherefrom. The tar returned to the coke oven and there distilled isdecomposed to a greater or less extent with resulting production of moreor less carbon in finely divided form and various decomposition productswhich mix with the gases and vapors from the coking of the coal andmodify their composition. When these gases are cooled to recover tartherefrom, the tar will be a modified tar, modified by the products ofdistillation and decomposition of the tar returned to the coke oven.

In the ordinary operation of a by-product coke oven plant the individualovens are charged in rotation and the entire block or battery of ovensis kept at a high temperature by heating fiues suitablylocated betweenthe ovens. At the end of the coking operation the incandescent coke ispushed from the oven and a fresh charge of coal is introduced into theincandescent oven. The coking operation requires a considerable periodof time, for example, twelve to twenty hours more or less. During theearly portion of the coking period a large amount of so-called richgases is produced, rich in tar constituents, while during the laterportion of the coking period a smaller amount of so-called lean gases,lower in tar constituents, is produced.

In carrying out the present process the tar or pitchto be distilled isadded to the coke oven after the coal is charged to the oven. It may beadded soon after the coal is charged and before the coal charge has beenheated to incandescence, in which case the liquid tar or pitch will rundown into and through the coal charge to a greater or less extent. It ismore advantageous, in most cases, to add the tar or pitch after cokingof the coal has begun and progressed far enough so that the upper layersof the charge are incandescent and so that the tar or pitch introducedwill be rapidly distilled and coked in the incandescent upper portion ofthe oven. When tar or pitch is introduced under such circumstances it israpidly distilled and the residue is rapidly coked. The gases and vaporsresulting from the distillation and coking of the tar or pitch mix wiihthose resulting from the coking of the coal and are drawn off therewithand cooled for the recovery of the normal tar constituents of the gasesand the products of distillation and decomposition of the tar or pitchdistilled.

The process of the present invention is of special value for thetreatment of low carbon tars to produce tars of higher carbon content.Water gas tar, for example, which is low in carbon content can besprayed into the incandescent top of I the coke oven and distilled andmore or less cracked or decomposed to give a coke residue which remainsbehind as a part of the coke produced in the oven and to givedistillation and decomposition products including more or less freecarbon and cons'ituents commonly classified as free carbon. When suchtar is introduced into the top of the incandescent coke oven at the endof the oven remote from that from which the gases are drawn off to thecollecting system the vapors and gases resulting from the distillationand decomposition of the tar will be carried through the incandescentupper portion of the coke oven where additional cracking anddecomposition may take place before they escape from the incandescentzone into the uptake pipes and collector main. When such decompositionproducts are carried from the ovens by the gases the decompositionproducts increase the free carbon in the tars obtained on cooling thegases. Simi larly, coke oven tar can be distilled and more or lessdecomposed to give products of increased free-carbon content similar tothe tars produced from high temperature gas retorts. carbon tars are ofvalue for special purposes such as the production of high carbonpitches.

Increase'in the free carbon content of the tar produced may be efiectedby adding the tar in such a way-fo'r example, by spraying it in finelydivided formthat considerable entrainment of the products ofdecomposition by the gas stream takes place. the tars produced from thegases.

A tar of high free carbon content may result from the addition to thegases leaving the ovens of either dec'omposiion products resulting fromdecomposition of vapors resulting from the distillation of tar, orfinely suspended residue rewill also be produced as a result of suchdistillation and decomposition, this coke being added to and more orless blended with the coke produced from the coal.

Instead of introducing raw tar intothe coke oven to distill it accordingto the present invention the tar can be first dehydrated or bothdehydrated and partly distilled before being so used. The tar can, forexample, be distilled in another still such as one using the hot colseoven gases and in which the tar is brought into intimate and directcontact with the hot coke oven gases after they have left the coke oven,and the resulting pitch can then be introduced into the incandescent topof the coke oven to further distill it and produce coke and additionaldistillate therefrom. In such case distillation and decompositionproducts will pass with the gases from the coke oven into the gascollecting syslem, and the tar separated from the gases will be modifiedby its content of such distillation and decomposition products. I

Instead of collecting the tar from such gases in the ordinary way thegases can be cleaned at a high temperature by passing them through a hotpitch scrubber or anelectrical precipitator at a high temperature toseparate more or less of the suspended pitch particles from the gasesafter which the gases can be cooled to condense clean or relativelyclean (i. e., pitch-free) oils therefrom, such as creosote oil orcreosote and carbolic oils, etc. In such case a special pitch Will bedirectly recovered from the hot gases as well as marketable oils. Thehot gases from the coking and distilling operation can also be employedfor the distillation of additional tar or for the preliminarydistillation of tar to form pitch which is to be subsequently introducedinto the coke ovens and there cohed.

In general, in introducing the tar or pitch into the incandescent top ofthe coke oven it should be spread out more or less ormly to avoid localovercooling of the coke by an excess of localized tar or pitch. The taror pitch can, however, be

introduced at localized zones, for example, by-

introducing it at the end of the colre oven away from the point at whichthe gases and vapors Such high' 'These appear as free carbon in' wallsof the oven and the charge in the oven over a prolonged period of timebefore being removed from the oven. The amount of tar or pitch which canbe distilled in any one oven can be varied within rather wide limits. Ifa large amount of tar is to be distilled suficient additional heat mustbe required or less coal charged into the oven so that part of theheat'normally available for coking coal will instead be used for thedistillation and decomposition and coking of the tar or pitch residue.

When the tar or pitch is introduced in the form of small streams or inthe form of coarse spray it will for the most part run down on to thecoking coal and be distributed over and through the charge of cokingcoal. If, however, the tar or,..pitch is sufficiently subdivided andintroduced in a sumciently fine state of subdivision into the hot gasesflowing through the top of the coke oven it will be largely or entirelydistilled and coked while in suspension in or passing through the gases.1

The spraying or atomizing of the tar or pitch into the gases, in casethe distillation and col;-

Mid

ing are'to be largely carried out while the tar or pitch is suspended inthe gases, can be efiected in various Ways. The tar or pitch can, for example, be introduced through atomizing or nebulizing nozzles or devicesin such a fine state of subdivision that it will tend to remain insuspension in the gases flowing through the top of the coke oven. So,also, the tar or pitch can be atomized or nebulized into a current ofgas, such as coke oven gas, outside the coke oven, and the resultingcurrent of gas with suspended tar or pitch particles then introducedinto the incandescent upper portion of the colre oven to mix with thegases flowing therethrough. The tar or pitch can also be introducedthrough atomizing or nebulizing nozzles or devices in which coke ovengas is employed for assisting in the atomizing or nebulizing operation.

By suspending tar or pitch in a finely subdivided state in coke ovengases and then introducing the gases and suspended tar or pitchparticles into the incandescent upper portion of the oven, the gases sointroduced will blend with the hot gases in the oven and thedistillation and coking will take place to a greater or less extentwhile the particles remain in suspension and in this case the resultingparticles of cake or carbon from the coking oi the tar or pitch may to agreater or less extent remain in suspension in the gases leaving theoven. When llltl a current of coke oven gas with suspended tar or pitchis introduced into the oven it will in general be desirable to introduceit at the end of the oven remote from that at which the gases leavetheoven, that is, at the end of the oven opposite that at which the uptakepipe is lo= cated, thus increasing the gaseous 1; w .1. flow ing throughthe incandescent arch of the oven. When a suspension of tar or pitch incoke oven gas is introduced into the incandescent upper portion of theoven the suspended particles oi? tar or pitch will be heated by contactwith the hot gases coming oil from the coking oi the coal will leave theoven with the escaping gases and vapors.

The tar subjected to distillation according to the present invention maybe the total tar produced at the coke oven plant or it may be theheavier tar separated in the collector main or the lighter tar collectedin the condensers. Where the coke oven plant has rich and lean gasmainsfor collecting separately the rich and lean gases, the high carbon tarand low carbon .tar separated respectively from the lean and rich gasescan be kept separate and separately distilled; or the low carbon tarseparated from the rich gases during the early portion of the cokingoperation can be returned to the coke oven and distilled to give ahigher carbon tar. By distilling the low carbon tar in the coke ovensduring the later portion of the coking operation when lean gases arebeing given off therefrom the tar separated from the gases .will be ahigher carbon tar. In this way it is possible to distill separately thelow carbon tar so that only relatively high carbon tar will be recoveredat the coke oven plant. Likewise by collecting the heavy tar from thecollector main in lean gases tar of much higher carbon content may beproduced.

The invention will be further described in connection with theaccompanying drawing which shows in a somewhat diagrammatic andconventional manner part of a by-product coke oven plant adapted for thecarrying out of the process of the invention.

In the accompanying drawing, Fig. 1 is an elevation, partly in section,showing one of the coke ovens and the by-product recovery system,

, and Fig. 2 is a section taken at right angles to the view of Fig. 1 onthe line 2-2.

The drawing shows one of the ovens of a coke oven battery 5 with eachoven connected through an uptake pipe 6 and goose-neck 7 with acollector main 9. Each oven is provided wi h charging openings 12. Theindividual ovens are heated by heating flues 15, shown conventionally,these heating flues being connected with the regenerators 16 which arealternately heated-by the products of combustion and used to preheat theair and gas employed for combustion.

The collector main 9 is connected by a crossover main 19 with suitablecondensers indicated at 20 and shown as condensers of the direct type inwhich the gases are sprayed wi h ammonia liquor and from which the tarryoils and ammonia liquor are drawn off into the decanter 21, the tarryoils being'collected in storage tank 22. From the condensers the gasespass to an exhauster 35 and to an ammonia absorber or saturator and thelight oil recovery system (not shown).

The gases in the collector main 9 may be cooled by sprays of ammonialiquor introduced at 10. The tar and ammonia liquor collecting in thecollector main are drawn of! through the pipe 11 to the decanter 31 fromwhich the tar is drawn of! to storage tank 32.-

The coke oven construction and operation thus far described is the usualconstruction and operation. The coke oven gases from the individualovens pass to the collector main where 1 they are cooled by sprays ofammonia liquor and candescent coke.

and scrubbed and a light tar separated therefrom. Thegases then pass toan ammonia absorber or saturatonetc.

The different ovens of a coke oven block or battery are charged inrotation, so that, for example, at the time one oven is pushed andrecharged, the adjacent ovens will be at diiferent stages of the cokingoperation. The coking of coal requires a considerable period of time,for example, around twelve to twenty hours more or less. During theearly portion of the coking period, the coal adjacent the side walls andat the top of the charge is first coked, and the coking progressestoward, the center and is continued until the entire charge of coal iscoked. The gases given oif by the coal during coking pass' to the top ofthe oven and along the top to the uptake pipe 6 where they pass to thecollector main and gas han g system. The arch at the top of the oven iscandescent and the topof the coke becomes incandescent when-the coal atthe top of the charge has become coked.

According to the present invention, the tar or pitch, etc., to bedistilled is introduced into the top of the coke ovens above the body ofincandescent coke 13 therein, and more or less uniformly distributedover the top of the in- In the drawing, a series of supply pipes 34 areshown, each having branches 33 leading into the top of the coke oven at,different places. The branches 33 are shown as being connected to thesupply pipes 34 through the toggle joints 33' in order that the branches33 may be removed from the ovens when not in use. The holes throughwhich they are inserted may then be plugged in any suitable way, and thejoints 33 and branches 33 may be allowed to lie flat on the top of theovens until required for further use. That portion of the branch pipes33 which is exposed to g reatest heat may be coated with a protectiverefractory coating or may be water-jacketed After the tar or pitch hasbeen admitted to the ovens the branch pipes 33 and preferably also thesupply pipes 34 when not in use are blown with a fluid such as steam toremove any tar or pitchremaining in the pipes to prevent decompositionand coking of such tar or pitch and clogging of the pipes.

It will be evident that the number of places at which the tar or pitchis introduced can be varied, and that the particular type of outlet orother device employed for distributing the tar or pitch over theincandescent coke and into the gases in the upper portion of the ovencan be varied. The tar or pitch is introduced in liquid state, and isdisseminated or distributed in the upper portion of the oven. As the taror pitch comes into contact with the current of gases passing throughthe incandescent upper portion of the oven, the distillation and cokingmay take place by heat imparted to the tar or pitch by conduction fromthe gases and by radiation from the incandescent coke and oven walls.The tar or pitch which is not so distilled and coked is deposited on theincandescent coke and is there distilled and coked. The tar or pitchintroduced into the incandescent upper portion of the coke oven, is thussubjected to direct contact with the hot gases, to direct contact withthe incandescent coke, and to radiant heat from the incandescent arch ofthe ovens and from the coke. As a result, the tar or pitch is rapidlyheated and distilled and coked. The high temperature to which the tar orpitch is subjected, not only rapidly distills the same, but brings aboutmore or less decomposition of the constituents of the tar or pitch, sothat considerable gas is formed, as well free carbon, or lamp black, orconstituents which appear in the tar as so-called free carbon. The gasesand vapors, including gaseous and vaporous decomposition products, mixwith the gases givenofi by the coal, and the mixed gases pass to the endof the ovens from which they are withdrawn, and then pass through theuptake pipes to the collector mains. The coke, residue remaining fromthe distillation and coking is will be required to pass the entirelength of the oven through the incandescent space-between the coke andthe arch, and additional decomposition will take place owing to the hightemperature to which the constituents are subjected.

The coke oven gases with the added gases and vapors from thedistillation and coking of the tar or pitch pass from the individualovens to the collector main where they may be cooled to sep= arate aheavy tar therefrom after which the gases pass to the condensing systemwhere they are furthercooled to separate a light tar therefrom. The tarsso collected will be modified in composition, as compared with thosenormally recovered, by the presence therein of the distillation anddecomposition products produced from the tar or pitch added to the cokeovens, thus giving, for example, tars of higher carbon content,

or tars from which pitches of higher carbon content can be obtained, andalso giving tars with higher content of valuable oils.

It will beevident that the rate at which the tar or pitch is introducedand distilled can be varied, for example, by varying the period, during.the later part of the coking operation, during which tar or pitch isintroduced. So also, from the standpoint of the coke produced, a greateror less amount of pitch coke can be formed, for example, by charging theoven with somewhat less than the normal charge of coal, and adding asufiicient amount of tar or pitch so that, after distillation andcoking, the pitch coke no. from the tar or pitch will bring the cokeproduced up to the normal amount. In such case, the coke ovenmay, to avery considerable extent, serve for coking pitch at the same time thattars of modified composition are produced from the gases given oilduring the cog operation.

I claim:

l. The method of distilling tar or pitch and of coking coal in aby-product coke oven, which comprises charging the coal into anincandescent colre oven and, after coal has been so cged and before thecoking cit the coal in the oven is completed, introducing the liquid tobe distilled into the upper portion of the coke oven, heating the liquidand coal so m to distill the liquid and coke the distillation residue dsi= multaneously coke the coal in the oven, and withdrawing vaporsresulting from the ills tion and cc of the liquid in :w

sulting from t nocaova gases and vapors resulting from the kind, thecoal. l

2. The method of 12. m" tar or pitch which comprises introduc the liquidto be cc into the upper portion of a coke oven in which a coal chargeisbe seized, distg thcliquid while coking the coal and withdra the vaporsresulting from the distillation oi the liquid in admixture with gasesand vapors resulting from the coking oi the coal.

3. The method of fn. In; tar or pitch which comprises introducing theliquid to be distilled into the incandescent upper portion of abyproduct coke oven after coal has been 11, r" thereto and after thecoking of the coal in the oven has been begun, distilling the liquidwhile cokingthe coal and withdrawing from the oven the vapors resultingfrom the distillation of the liquid in v. .v; 1" ixture with gasesvapors resulting from the colnng oi the coal.

4. The method oi distilling tar or pitch and producing coke from theresidue, which comprises introducing the liquid to be distilled inregulated amount into the upper portion of a coke oven which is at acoking temperature and Mill contains coke formed from coal therein anddistributing the liquid over thecoke, so as to distill the liquid andcoke the residue, and withdrawing the gases and. vapors from thedistillation and coking of the residue in ature with ltd gases andvapors resulting from the coking oil the coal.

5. The method of distg tar or pitch and producing coke from the residue,which com= prises coking coal in incandescent coke oven llll) andintroducing the liquid to be distilled into the incandescent upperportion of the coke even during a later portion of the .co 1:1" oi thecoal therein. I I

d. The method of distilling tar or pitch and lid producing therefrom andfrom coke oven gases tars or high free carbon content, which com= prisesconverting the liquid to coke by introducing it in regulated amount intothe incandescent upper portion of a coke oven in which coal is be= 21iing colred, withdrawing from the oven the and vapors resulting from theco ol the liquid and the coal and coog the some to re-- cover high freecarbon tar therefrom.

7. The method of dist tar or pitch which lid ii comprises introducingthe liquid to be diet in an atod or neb state into the hot gases pg thehot upper portion oil a'by-product'colze oven in which a charge of rcoal is being colzed after the coal charge has been partly colredtherein so m to distill the liquid by heat parted thereto by conductionlrom the gases and by radiation from the hot echo and oven walls whileout of contact with both the coke and oven w, and withdmwlng 1% from theoven vapors r from the do tion of the liquid in m. Jul. ure with mudvapors resulting from the co oi? the coal.

it. The method oi dist tar or pitch which comprises atom or nebul theliquid to lei? be deed in a current oigas to form a sion off it in thegas, ca such on to mix with hot gases pas ugh the lump descent upperportion of a by-product coke oven in which a cc of coal is being cohedat the 31% charge has been partly colzed therein tin by rapidly ill theliquid by contact with the hot and by ration from the coal and oven, andm 2 from the oven vapors re illation of the liquid in ad 11 mixturewithgases and vapors resulting from the coking of the coal.

' 9. The method of distilling tar or pitchin a byproduct coke oven whichcomprises atomizing or nebulizing theliquid to be distilledso as to forma suspension of it in the gases and vapors in the top of a coke oven inwhich a charge of coal is being ooked afterthe coal charge has beenpartly coked therein, rapidly heating and distilling the liquid bycontact with the hot gases and by radiation from the coal and oven,carrying residue from such distillation from the oven by the gases andvapors resulting fromthe distillation of the liquid and the coking ofthe coal in the oven, and

- cooling the gases and vapors with said residue suspended therein so asto recover tar comprising such residue.

10. The method of distilling tar or pitch in a by-product coke ovenwhich comprises atomizing or nebulizing the liquid to be distilled toform a suspension of it in the gases and vapors in the top of a cokeoven in which a charge of coal is being coked after the coal charge hasbeen partly coked therein, rapidly heating and distilling the liquid bycontact with the hot gases and by radiation from the coal and oven,carrying residue from.

such distillation together with solid products resulting fromdecomposition of vapors distilled from the liquid from the oven by thegases and vapors resulting from the distillation of the liquid and thecoking of the coal in the oven, and cooling the gases and vapors withsaid residue and decomposition products suspended therein so as torecover tar comprising such residue and deduced by the coking ofcoalinother ovens of the battery to which none of the liquid has been added,and cooling the combined gases and vapors to separate tar therefrom.

12. The method of distilling tar or pitch and producing coke and tartherefrom, which comprises coking a'charge of coal in a coke oven untilcoke has formed from a considerable part of the coal, introducing theliquid to be distilled into the incandescent upper portion of the cokeoven dur-' ing a later portion of the coking of the coal therein,thereby heating and distilling the liquid and coking the residue,withdrawing the gases and vapors given oif from the liquid and the coalduring such distillation together with gases produced during thedistillation of coal in another I oven to which no liquid has beenadded, and cooling the same to recover tar therefrom. 13. The method ofdistilling tar or pitch whi comprises introducing the liquid to bedistilled in an atomized or nebuiized state into the hot gases passingthrough the incandescent upper portion of a by-product coke oven inwhich a charge of coal is being coked after the coal charge has beenpartly 'coked therein so as to distill the liquid by heat impartedthereto by conduction from-the gases and by radiation from theincandescent coke and oven walls while out of contact with both the cokeand oven walls, allowing distillation residue to settle out of the gasesonto the top 01'- the coal charge, coking the residue and with,- drawingfrom the oven vapors resulting from the distillation of the liquid andgases and vapors resulting from the coking of the distillation residuein admixture with gases and vapors resulting from the coking of thecoal.

14. The method of distflling water gas tar which comprises introducingwater gas tar into the upper portion of a coke oven in which a charge ofcoal is being c'okd, distilling the tar while coking the coal andwithdrawing fromthe oven vapors resulting from the distillation of thetar in admixture with gases and vapors resulting from the coking of thecoal. 7

STUART PARMELEE MIILER.

Y fat

